• Title/Summary/Keyword: low tension

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A STUDY ON NUMERICAL SIMULATION OF TOWED LOW-TENSION CABLE WITH NONUNIFORM CHARACTERISTICS (불균일 단면을 갖는 저장력 예인케이블에 관한 수치해석적 연구)

  • Jung, Dong-Ho;Park, Han-Il
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.161-166
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    • 2002
  • Low-tension cables have been increasingly used in recent years due to deep-sea developments and the advent of synthetic cables. In the case of low-tension cables, large displacements may happen due to relatively small restoring forces of tension and thus the effects of fluid and geometric non-linearities become predominant. In this study, three-dimensional (3-D) dynamic behavior of a towed low-tension cable with non-uniform characteristics is numerically analyzed by considering fluid and geometric non-linearities and bending stiffness. A Fortran program is developed by employing a finite difference method. In the algorithm, an implicit time integration and Newton-Raphson iteration are adopted. For the calculation of huge size of matrices, block tri-diagonal matrix method is applied, which is much faster than the well-known Gauss-Jordan method in two point boundary value problems. Some case studies are carried out and the results of numerical simulations are compared with a in-house program of WHOI Cable with good agreements.

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The Effects of Green Tea Catechins on Vascular Smooth Muscle Tension and 45 $Ca^{2+}$ Uptake (녹차 카테킨류의 혈관장력 및 $Ca^{2+}$유입에 미치는 영향)

  • 안희열;이미애;윤여표
    • Journal of Food Hygiene and Safety
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    • v.11 no.2
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    • pp.83-87
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    • 1996
  • The objective of this study is to investigate the direct effects of green tea catechins(GTC) on vascular smooth muscle tension and 45Ca2+ Uptake in rat aorta. The methods used in this study are isometric tension measurements using physiograph, Lanthanum method for 45Ca2+(2 uCi/ml) uptake measurement in rat aorta. GTC modified tension induced by 40 mM KCl or 1 uM norepinephrine in rat aorta. Low concentrations of GTC(<0.5mg/ml) increased tension by 40 mM KCl or 1 uM norepinephrine, individually. However, high conecentration of GTC(>0.5 mg/ml) inhibiited tension by 40 mM KCl or 1 uM norepinephrine, individually. GTC increased 45Ca uptake induced by 40 mM KCl in a dose-dependent manner. From these results, GTC has the dual actions in vascular smooth muscle in vitro. Low concentrations of GTC augments tension by K or norepinephrine. However, high concentrations of GTC inhibits tension by K or norepinephrine GTC may have Ca2+ channel activation, action, which may result in unphysiological vasodilation by Ca2+ overload in vascular smooth muscle.

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The Elongation Method for the Measuring Surface Tension of High Viscosity Printing Ink (인장법에 의한 고점도 잉크의 표면장력 측정법)

  • Ha, Young-Baeck;Youn, Jong-Tae;Koo, Chul-Whoi
    • Journal of the Korean Graphic Arts Communication Society
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    • v.21 no.2
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    • pp.89-100
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    • 2003
  • We have reviewed the method for surface tension of printing inks. Most of the methods fir for the low viscosity inks and solvents for inks. However, the inks for the offset lithography and intaglio should have high viscosity and high tack. The elongation of the ink filaments has more effect on the measuring surface tension than the energy of the surface molecules. In this paper, we propose the elongation method to estimate the surface tension of high viscosity printing inks. Even though we could measure the surface tension for low viscosity inks such as gravure and screen, elongation method could more useful to estimate the surface tension of lithography and intaglio inks than any other methods.

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Effect of Low Molecular Weight Species on the Interfacial Tension of PC/SAN Blend (PC/SAN 블렌드의 계면장력에 미치는 저분자량 성분의 영향)

  • Yang, Dongjin;Son, Younggon
    • Polymer(Korea)
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    • v.39 no.3
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    • pp.388-393
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    • 2015
  • Low molecular weight species were extracted from PC and SAN by a solvent extraction method in order to investigate the effect of low molecular weight species on interfacial tension and affinity between PC and SAN. From the analysis of molecular weight distribution by the GPC, it was confirmed that the low molecular weight species were effectively eliminated by the solvent extraction. Interfacial tension measurements and morphological observation were carried out with the PC and SAN of which the low molecular weight species were extracted. Interfacial tension was increased and the infinity was decreased for the extracted PC and SAN pair. This result implied that the low molecular weight species play a role as a compatibilizer between two polymers. Among two polymers, low molecular weight SAN contributes more in the compatibilization. Thus, it is favorable to use SAN containing a larger amount of low molecular weight species in fabrication of PC/ABS blend.

Design of LTBC Controller for Tension Control in Down Coiler Process of Hot Strip Mills (열간압연 권취공정의 장력제어를 위한 LTBC 제어기 설계)

  • Lee, Sang Ho;Park, Hong Bae;Park, Cheol Jae
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.4
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    • pp.301-308
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    • 2015
  • In this paper, we propose an LTBC (Low Tension and Load Balance Control) scheme to improve a coiling shape control by reduction the tension fluctuation by the torque disturbance in the down coiler process of hot strip mills. The proposed controller is a combination of an LTC to control the overload at load-on in the mandrel and an LBC to regulate the load balance of the upper and bottom pinch roll. A tension calculation model is suggested with the concept of the tension deviation. The effectiveness of the proposed control scheme is verified from simulation under a disturbance of the pinch roll torque. Using a field test, we show that the performance of the shape and tension control is improved by the LTBC control.

The Opening Size Change for Screen Tension (스크린 망사의 견장과 오프닝의 변화)

  • Jung, Gi-Young;Kang, Young-Reep
    • Journal of the Korean Graphic Arts Communication Society
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    • v.28 no.1
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    • pp.43-50
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    • 2010
  • The 200mesh screen was tensioned and fixed on a frame. When applied tension to 5N and 10N per unit area, a side length of opening of the screen was 163.223${\mu}m$ and 168.224${\mu}m$, respective. But side length not tensioned was 158.879${\mu}m$. We knew that a side length of opening of the screen rarely changes with tension applied to the screen. The appearances that a side length of opening of the screen expand little are due to a decreasing diameter of thread by means of tension. In a thickness measurement of screen, While the high density mesh screen that had a lot of knots that crossed a line of latitude and longitude per unit area appeared a higher numerical value, the low density mesh screen that had a few knots appeared a low numerical value.

A Numerical and Experimental Study on Dynamics of A Towed Low-Tension Cable

  • Jung, D.H.;Park, H.I.;Koterayama, W.
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.191-196
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    • 2002
  • The paper presents a numerical and experimental investigation on dynamic behaviors of a towed low tension cable. In the numerical study, an implicit finite difference algorithm is employed for three-dimensional cable equations. Fluid and geometric non-linearity and bending stiffness are considered and solved by Newton-Raphson iteration. Block tri-diagonal matrix method is applied for the fast calculation of the huge size of matrices. In order to verify the numerical results and to see real physical phenomena, an experiment is carried out for a 6m cable in a deep and long towing tank. The cable is towed in two different ways; one is towed at a constant speed and the other is towed at a constant speed with top end horizontal oscillations. Cable tension and shear forces are measured at the top end. Numerical and experimental results are compared with good agreements in most cases but with some differences in a few cases. The differences are due to drag coefficients caused by vortex shedding. In the numerical modeling, non-uniform element length needs to be employed to cope with the sharp variation of tension and shear forces at near top end.

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Properties of Low Density Foamed Concrete for Building Construction Using Anionic Surfactants of Synthetic and Natural Materials

  • Jeong, Ji-Yong;Kim, Jin-Man
    • Journal of the Korea Institute of Building Construction
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    • v.11 no.6
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    • pp.557-566
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    • 2011
  • The surfactants facilitate the formation of foam bubbles under a proper condition and provide stability of foam bubbles by decreasing the surface tension of solutions and increasing the viscosity of foam surface. However, there have been almost no practical data of foam concrete in this regard so far. This study aims to understand the effects of foaming agents such as anionic synthetic surfactant and anionic natural material surfactant on the low density foamed concrete. From the experiment, the vegetable soap of anionic natural material surfactants showed a higher foaming rate, more open pores, slightly lower compressive strength, and a higher permeability coefficient compared to the vegetable soap of anionic synthetic surfactants. It is believed that the natural material surfactants make not only the surface tension of the solution low but also the viscosity of slurry high.

A Study on the Atomization Characteristics of the Ultrasonic-Energy-Added Low Viscosity Biodiesel Blended Fuel (초음파(超音波) 에너지 부가(附加) 저 점도 바이오디젤 혼합연료(混合燃料)의 미립화 특성(微粒化 特性)에 관한 연구(硏究))

  • Song, Yong-Seek;Kim, Yong-Cheol;Ryu, Jung-In
    • Journal of ILASS-Korea
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    • v.9 no.3
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    • pp.1-7
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    • 2004
  • This experiment was undertaken to investigate the atomization characteristics of the low viscosity biodiesel blended fuel and ultrasonic energy added one. Test fuels were conventional diesel fuel and biodiesel fuel. We compared to the characteristics of viscosity and surface tension, SMD between low viscosity biodiesel blended fuel and ultrasonic energy added one. Sauter mean diameter was measured under the variation of the spray distance. Viscosity and surface tension was measured under the variation of the time trace. To measure the droplet size, we used the Malvern system 2600C. Droplet size distribution was analyzed from the result data of Malvern system. Through this experiment, we found that the condition of the ultrasonic energy added situation had smaller Sauter mean diameter of droplet, viscosity and surface tension than that of the conventional situation.

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MUSCLE PROTEIN SYNTHESIS IN VITRO IN CHICKS FED A LOW-PROTEIN DIET

  • Kita, K.;Kuzuya, Y.;Matsunami, S.;Okumura, J.
    • Asian-Australasian Journal of Animal Sciences
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    • v.9 no.2
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    • pp.171-174
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    • 1996
  • Muscle protein synthesis in vitro was measured in chicks fed low-protein(10% CP) and control(20% CP) diets. Right leg muscles (M. gastrocnemius) were mounted on a support made of stainless steel to stretch in constant tension, whereas left leg muscles were unmounted. Both leg muscles were incubated in Dulbecco's modified Eagle's medium including L-[$4-^3H$] phenylalanine for 60 min to measure in vitro protein synthesis. There was no significant difference in fractional synthesis rate(FSR) of muscle protein between both dietary protein levels, whereas FSR with stretch in constant tension was significantly higher than that without constant tension due to an increase in the absolute synthesis rate(ASR) per unit RNA(the efficiency of RNA to synthesize protein). The ASR of muscle protein in chicks fed the control diet was significantly higher than that in the low-protein diet group.